Paper Title:
Colloidal Processing of SiC with Rare-Earth Ion
  Abstract

The SiC powder of median size 0.8 µm was mixed with polyacrylic acid (PAA, dispersant) in a 0.3 M-R(NO3)3 solution (R=Yb, Y, Gd, Sm, Nd and La) at pH 5 to adsorb uniformly the sintering additive (R3+ ion) on the SiC surface. The addition of PAA to the SiC suspension with R3+ ion increased the amount of R3+ ion fixed to SiC particles. The aqueous 30 vol% SiC suspension with 0.52 mass% PAA and 1.50 mass% R2O3 (as R3+ ion) against the mass of SiC, was consolidated by filtration through a gypsum mold to form green compacts of 50-52 % of theoretical density. The consolidated green compacts were hot–pressed under a pressure of 39 MPa at 1950°C for 2 h in an Ar flow. The green compacts were densified with grain growth to 76 - 99 % relative density. The addition of smaller R3+ ion was effective to enhance the sinterability of SiC and also to achieve smaller grain size of SiC. The sintering mechanisms were discussed based on the analysis of the shrinkage curves of SiC/R2O3 compacts during the hot-pressing.

  Info
Periodical
Edited by
Hai-Doo Kim, Hua-Tay Lin and Michael J. Hoffmann
Pages
123-128
DOI
10.4028/www.scientific.net/KEM.287.123
Citation
S. Tabata, Y. Hirata, S. Sameshima, Y. Uemura, "Colloidal Processing of SiC with Rare-Earth Ion", Key Engineering Materials, Vol. 287, pp. 123-128, 2005
Online since
June 2005
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$32.00
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